Active electronic components and integrated circuits are increasingly significant in modern controllers, communications equipment and related or compatible systems. Electronic component manufacturers are constantly striving to increase the performance of their products, while decreasing their cost of manufacture. Economic concerns and market forces driven by larger system and computation desires result in the desire for increasing circuit complexity and breadth of functionality. These concerns and forces, including size and power efficiency considerations, may place constraints on the elements and functions that are combined in realization of such circuitry.
Aligning these various factors, while effectuating cost containment and yet providing improved operational parameters, results in challenges that have spawned a variety of specialized approaches for individual sets of design/performance goals.
General trends towards progressively smaller devices and reduced power consumption per circuit element may result in increased susceptibility of these devices to catastrophic failure. One weakness or “Achilles' heel” presenting vulnerability for many types of devices results from electrical stresses, which may originate from a variety of different phenomena, including electrostatic discharge (ESD) from environmental sources, voltage stresses originating from switching and other electronic functions in such circuitry, or circuitry coupled thereto, and may be exacerbated by ringing in electrical signal and power distribution and coupling circuitry, ground or other power-supply conductor potential disturbances, or by failure or malfunction of portions of circuitry coupled to an affected component. Susceptibility of electrical components to effects of electrical stress may increase as size of individual elements decreases, in part because progressively lower power supply voltages are consistent with these trends, and, as a result, components in these circuits are increasingly voltage-sensitive. Accordingly, these concerns collectively present competing challenges, particularly in view of performance targets for robustness and reliability of resultant electronic circuits.
Different surge or transient suppressor devices and designs have been developed, responsive to long-felt needs within the industry. Some approaches require relatively large areas for formation or may require additional processing considerations or fabrication elements (such as elements or processing considerations for masking operations). Other approaches may present parasitic electrical effects that in turn may affect circuit performance adversely or have performance characteristics susceptible to degradation or catastrophic failure in their intended application. In some approaches, provision of capacity for carrying sufficient electrical current may also result in unwieldy footprint requirements or reduced switching speed or both.
Accordingly, it would be desirable to have an improved electrical stress protection apparatus and a method to manufacture the apparatus that is cost efficient.
For simplicity of illustration and ease of understanding, elements in the various figures are not necessarily drawn to scale, unless explicitly so stated. In some instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present disclosure. The following detailed description is merely exemplary in nature and is not intended to limit the disclosure of this document and uses of the disclosed embodiments. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding text, including the title, technical field, background, or the following abstract.